x – 80 = 90 · 7 x – 80 = 90 · 5

x – 80 = 90 × 7

x – 80 = 630

x = 630 + 80

x = 710

x – 80 = 90 × 5

x – 80 = 450

x = 450 + 80

x = 530

Ответ: x = 710; x = 530